This year, 2015, was a pivotal year in the annals of the effort to combat climate change.

The University of Maine’s Climate Change Institute published an updated assessment of climate change’s impacts on Maine’s weather, ecosystems and resource-based economy. The U.S. Senate voted 98-1 for a resolution finding that “it is the sense of the Senate that climate change is real and not a hoax” but rejected a resolution finding that it was significantly caused by humans. This year is the hottest year globally on record, markedly exceeding the previous six hottest years. A civil war in Syria born in severe drought, dislocation and unemployment has spawned terrorism and a dire refugee crisis. Pope Francis issued an imperative call to action on climate: “Obstructionist attitudes … can range from denial of the problem to indifference, nonchalant resignation or blind confidence in technical solutions. We require a new and universal solidarity.” President Barack Obama finalized his Clean Power Plan. And delegates from 195 countries convened in Paris to seize the “last, best chance” to forge a global plan to reduce greenhouse gases.

A clear majority of Maine residents, 67 percent, are concerned about the effect of global warming on Maine. We have a long tradition of sending strong environmental leaders to Congress who have played a leading role in fashioning key legislation such as the Clean Air Act and Clean Water Act. How have our current congressional representatives tackled the climate conundrum in 2015? I spoke recently with three of them. The results were impressive and, in one respect, quite surprising. Peter Mills and I will submit a full analysis of these conversations to the Maine Policy Review for its Spring 2016 issue.

Sens. Susan Collins and Angus King, and Rep. Chellie Pingree all earned As for their 2015 climate work. Our senators are among the most outspoken in Congress on climate science and the need for an effective response. King devoted his debut speech in Congress to the high risks of ignoring climate science and in 2015 delivered a floor speech echoing the Pope’s call for environmental stewardship based on fundamental moral precepts. Collins led a panel discussion on climate in Portland with a strong sense of urgency. All three voted against the effort to kill the Clean Power Plan.

All are cautiously optimistic about a shift away from partisan climate denial. In September, 11 House Republicans signed on to a resolution to fight climate change, and in October four Republican senators formed a climate working group.

“I believe that more and more Republican members are seeing the impacts in their own state,” Collins told us, “particularly those who live in coastal states and are becoming increasingly concerned.”

“There’s a sense that the edifice of denial is crumbling and that we are finally getting to a place where we can say climate change is happening,” King said.

But forging bipartisanship requires astute leadership at the top. Collins called it a “big mistake” when the Obama administration invited 10 congressional leaders to the Paris talks — all Democrats. I agree.

My climate grade for Rep. Bruce Poliquin is an “incomplete.” He was unavailable to speak with me and has not provided written answers to my interview questions. A comment in a campaign five years ago caused him to be labeled a denier, and he has not clearly disavowed that characterization. He voted to override the Clean Power Plan, but his colleagues characterize him as an enthusiastic participant in efforts to win federal dollars for efficiency and renewable energy projects. I hope Poliquin is still on a learning curve.

This brings me to the most surprising and concerning finding in my interviews. All four have earned an “incomplete” grade in one important respect: talking with each other about things that matter. None of our climate champions in Congress has had discussions with Poliquin about climate science or policy. Collins’ response was typical: “While Bruce and I talk quite frequently, he has not sought my advice on that issue, nor have we had any discussions at all.” I know these conversations are difficult, but I don’t think it’s too much to ask for our delegation to sit down, converse and attempt to forge a “tripartisan” front on this most dire threat.

Sharon S. Tisher is a lecturer in the School of Economics and the Honors College at the University of Maine. She is a member of the Maine chapter of the national Scholars Strategy Network, which brings together scholars across the country to address public challenges and their policy implications. Members’ columns appear in the BDN every other week.